LPV Control and Singularity Avoidance of a Spacecraft with DGCMGs

In this paper, we analyze the dynamics of a spacecraft with Multiple Double-Gimbal Control Moment Gyros (DGCMGs). After local linearization of this nonlinear dynamics, we develop an easy-to-use Linear Parameter-Varying (LPV) model, in which we deal with 3-axis attitude control of a spacecraft equipped with two parallel DGCMGs. Then, we propose a singularity robustness (SR) steering law together with a sigmoid function as a singularity robust parameter. Although it is hard to consider overall stability and control performance of attitude control at the same time with conventional Lyapunov function-based controllers, this paper attains both of approximate stability and control performance via LPV control theory, while using redefining the control input of the generalized plant. Through a numerical example, usefulness of the proposed method is demonstrated.